Apparatus and method for installing underground utility piping

ABSTRACT

In a method for installing underground piping, a pipe installation apparatus is temporarily positioned at one end of a pipe trench, in which bedding sand has been placed. The apparatus has a pipe opening through which pipe can pass, and a plurality of rubber-tired pipe wheels arrayed around and biased radially inward toward the pipe opening. At least one wheel is a motor-operated drive wheel. A section of pipe introduced into the pipe opening will be tractively engaged by the drive wheels and pushed through the pipe opening and into the trends The drive motors are disengaged as required for connection of additional pipe sections, or for placing temporary spacers in the pipeline to facilitate subsequent installation of required pipeline fittings. The leading end of the pipeline engages a sled which rides over and levels die bedding sand while preventing the pipe from digging into the sand. The need for workers to enter the pipe trench is thus reduced or eliminated, making it possible to safely install piping in steep-walled trenches.

FIELD OF THE INVENTION

The present invention relates in general to apparatus and methods for installing underground piping such as water and sewer mains, and in particular to apparatus and methods for installing such piping in narrow trenches.

BACKGROUND OF THE INVENTION

There are three methods commonly used for installing buried utility piping such as water and sewer mains. The “sale trench” method involves excavating a trench with its sides sloped at sufficiently shallow angles such that the potential risk of cave-ins is effectively eliminated. While providing optimal safety to workers, the safe trench method entails excavation of very large volumes of soil and the placing and compacting of corresponding large amounts of backfill. Because of the safe trench's sloped sides, this method disturbs and disrupts the use of a comparatively large surface land area.

The “trench shield” method reduces the necessary amount of excavation by using a heavy shield or enclosure, to protect workers in the trench. The shield is reinforced to resist forces and pressures that would be exerted against the shield in the event of a cave-in, making it safely feasible to use a trench that is narrower than a safe trench, and without needing the trench sides to be backsloped (or at least not as shallowly as a safe trench). The shield is moved along the length of the trench as new sections of pipe are added to die pipeline, to protect the work area surrounding each newly-added pipe section. The trench shield method thus provides safety to workers while reducing excavation and backfill requirements, but it has significant drawbacks nonetheless. Although, the trench can be narrower and less sloped than in the safe trench method, it still needs to be quite wide in order to accommodate the shield. Moving the shield, each time a new pipe section is added, entails a considerable amount of time, effort, and expense. These factors are exacerbated by the fact that the shield is necessarily quite heavy, especially if it is made long enough (as is preferable) to protect along the full length of a typical pipe section (which is commonly six meters long).

The third conventional method of installing underground piping is by inserting the pipe into a pre-bored hole. This method is very expensive, and its practical feasibility in a given situation will depend on a variety of variable factors (such as soil properties).

For the foregoing reasons, there is a need for pipe installation apparatus and methods that are practically and economically feasible in a broad range of field conditions, while requiring less excavation than conventional trenching methods and ensuring optimal worker safety. The present invention is directed to this need.

BRIEF DESCRIPTION OF THE INVENTION

In general terms, the present invention encompasses a method and apparatus for installing piping (especially jointed piping) in a narrow and substantially straight-walled trench, without need for workers to enter the trench. A first piping trench section is excavated to a desired length, using conventional equipment such as a track-mounted backhoe (also referred to as a trackhoe), with a bucket width typically in the range of 36 inches. Preferably, the bucket has a “spoon” attachment which farms a narrower secondary channel (or “sub-trench”) centered in the trench, for receiving piping. An equipment set-up area (or “working zone”), typically having a length of about 10 meters, is excavated at one end of the first trench section, for receiving the pipe installation apparatus of the present invention. The working zone is excavated in accordance with “safe trench” methods, to ensure the safety of workers operating the apparatus. Sand bedding is deposited into the trench (or, in the preferred embodiment, into the sub-trench), by workers and/or equipment at ground level. This process can be facilitated by having bedding sand deposited in small piles along the projected route of the trackhoe, prior to trench excavation. Upon completion, of excavation of a given section of trench, the hoe operator can scoop up some of the piled sand and deposit it in the trench (or sub-trench).

A first section of pipe is fed into the pipe installation apparatus, which is actuated so as to push the pipe section into the piping trench. The leading end of the pipe section is supported on a pipe sled which it pushes over the sand bedding as the pipe is pushed into the trench. The leading edge of the pipe sled has an upward curve or is otherwise configured to prevent the pipe from digging into the sand bedding, and at the same time serves to level and at least partially compact the sand bedding. When the apparatus has pushed the first pipe section into the trench, a second pipe section is fed into the apparatus and coupled to the first pipe section, and the apparatus then pushes the joined pipe sections further into the trench. Additional pipe sections are added until a pipe string has been laid along the full length of the first trench section.

A second trench section may then be excavated, along with an associated second working zone. The pipe installation apparatus is moved to the second working zone and is actuated to install a pipe string in the second trench section until it meets the pipe string previously laid in the first pipe section, and the two pipe strings are coupled to each other. The procedure is repeated as necessary to complete the full pipeline required for the project.

The method of the invention also provides for the installation of telescoping temporary spacers at locations along the finished pipeline where valves, tees, or other fittings need to be installed. Provision may he made for the safe installation of these fixtures during the trench excavation, by enlarging the trench to “safe trench” standards in the intended vicinity of fitting. The locations where temporary spacers need to be installed in the pipeline may be determined during pipeline installation operations using conventional measuring or surveying techniques. This may be facilitated by use of a known device such as a metering wheel or meter tally, mounted to the pipe installation apparatus, for measuring the length of pipe that has passed through the apparatus, thus enabling workers to make accurate determinations of where spacers should be installed. After a given string of piping and associated fittings has been positioned, a compressive force is applied to the string to firmly seat all joints between the various components. Most conveniently, this compressive force may he applied using the bucket of the trackhoe. The trench and all working zones may then be backfilled and compacted as required.

The present invention, also provides for a novel articulated packer apparatus especially adapted for compacting backfill in narrow trenches, such as in accordance with the method of the invention. The compaction apparatus may be independently self-propelled, or it may have a hydraulic drive system served by hydraulic fluid delivered by flexible hydraulic lines from the pipe installation apparatus. In preferred embodiments, the packer is remotely controlled so that it does not require an onboard operation, thereby further enhancing worker safety.

Accordingly, in a first aspect the present invention is an apparatus, for installing piping in a narrow trench.

In a second aspect, the invention is a packer for compacting backfill in a narrow trench.

In a third aspect, the invention is a method for installing piping in a narrow trench.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to the accompanying figures, in which numerical references denote like parts, and in which:

FIG. 1 is a perspective view of the pipe installation apparatus in accordance with a first embodiment of the invention.

FIG. 2 is a plan view of the apparatus- of FIG. 1, showing the outriggers in a stowed position.

FIG. 3 is a plan view as in FIG. 2, but with the outriggers in a deployed position.

FIG. 4 is an elevational cross-section showing a pipe being led through the pipe drive mechanism of the apparatus of FIG. 1.

FIG. 5A is an oblique partial section showing a pipe being fed through the pipe drive mechanism shown in FIG. 4, and illustrating the spring-actuated biasing means of the mechanism.

FIG. 5B is an oblique partial section as in FIG. 5A illustrating the actuation of the biasing means when a pipe coupling passes through the pipe drive mechanism.

FIG. 6 is a plan view of the apparatus of FIG. 1 positioned in a working zone and pushing a partially assembled pipe string into a trench.

FIG. 7A is a cross-section through a trench incorporating a secondary channel, shown with an optional laser support structure spanning the trench.

FIG. 7B is a cross-section through a working zone, incorporating a secondary excavation for housing the pipe installation apparatus of the present invention.

FIG. 8A is a side elevation of the apparatus in operation as in FIG. 6.

FIG. 8B is a side elevation of the leading end of a pipe string positioned in a pipe sled as shown in FIG. 6.

FIG. 9 is a cross-section through a piping trench during backfilling operations using a remote-controlled articulated packer in accordance with the invention.

FIG. 10 is a side elevation of the packer shown in FIG. 9.

FIG. 11 is an elevational cross-section of a pipe drive mechanism in accordance with a second embodiment of the invention.

FIG. 12 is a side elevation of the pipe drive mechanism of FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1, 2, and 3, the pipe installation apparatus of the invention (generally designated by reference character 10) has a base structure 20 adapted to rest on a generally level surface, with a transverse bulkhead 30 mounted to base structure 20 at a medial point along the length of base structure 20. In the Figures and in this specification, bulkhead 30 is representatively shown and referred to as a solid, plate-like structure, but that particular configuration is not essential to the invention. Bulkhead 30 could be of any suitably rigid construction, including an open framework. Accordingly, references herein to bulkhead 30 are to be understood in a non-restrictive sense, and to include transverse frames of other constructions.

Bulkhead 30 has a front side 30F and a rear side 30R. The configuration and construction of base structure 20 may take any form suitable for the functions described herein. In the illustrated preferred embodiment, base structure 20 is of generally rectangular outline (as viewed in plan), with a front end 20F and a rear end 20R. Base structure 20 has a pair of spaced side rails 21 extending between, a front frame 22F having a front frame opening 23F, arid a rear frame 22R having a rear frame opening 23R. Openings 23A and 23B are sized to suit the pipe to be laid using apparatus 10. Base structure 20 has a longitudinal axis extending between front end 20F and rear end 20R, approximately midway between side rails 21.

Front frame 22F and rear frame 22R each incorporate support legs 24, which optionally may include adjustment means (not shown) for adapting to uneven supporting surfaces. The adjustment means could comprise manually-operated screw-type or ratchet-type jacks, hydraulic cylinders, or any other suitable mechanism, various, types of which are well known in the art. The overall size and proportions of base structure 20 will depend on selected operational design parameters. In preferred embodiments, however, base structure 20 will be configured such that it can be readily transported in the box of a half ton truck.

Bulkhead 30 has a pipe opening 32 generally aligned with front frame opening 23F and rear frame opening 23R. Mounted in association with bulkhead 30 is a pipe drive mechanism, for engaging a pipe section 70 passing through pipe opening 32 and advancing it toward the front end 20F of base structure 20 and through front frame opening 23F. The pipe drive mechanism may take any of several different forms. In the embodiment shown in FIGS. 1-4, the pipe drive mechanism includes a plurality of drive wheels 34 spaced radially around pipe opening 32 in association with either the front side or the rear side of bulkhead 30. In the preferred embodiment (and as best seen in FIG. 4), each drive wheel 34 has its awn hydraulic drive motor 36. Drive wheels 34 preferably will be rubber-tired, to facilitate effective tractive engagement with pipe 70 without causing damage to the outer surfaces of pipe 70.

The pipe drive mechanism shown in FIGS. 1-4 has a total of four drive wheels, each with its own hydraulic drive motor 36. However, other pipe drive configurations are readily conceivable. To provide non-limiting examples of alternative configurations, the pipe drive mechanism could have three drive wheels, rather than four as shown. Another alternative embodiment could have four pipe-engaging wheels as shown, but with only two of the wheels being driven (preferably radially opposing each other) and with the other two wheels acting as idlers winch help guide the pipe 70 through pipe opening 32. Other embodiments could use only a single drive wheel. A further embodiment (shown in FIGS. 11 and 12, and described in detail later in this specification) would have six drive wheels mounted in pairs, with each pair of wheels driven by a single hydraulic motor by means of a pair of drive chains.

Simple embodiments of the pipe drive mechanism may have a fixed configuration for handling pipe of a specific diameter. In preferred embodiments, however, the pipe drive mechanism incorporates wheel adjustment means for adapting to different pipe sizes. In the embodiment shown in FIGS. 1-4, 5A, and 5B, the wheel adjustment means is provided by mounting each motor 36 on slide arm 38 which slides within a sleeve 40 which in turn is pivotably mounted to a bracket 41 connected to bulkhead 30. The radial position of slide arm 38 within sleeve 40 may be controlled by means of set screws or bolts 44 as illustrated, or by any other suitable and conventional means. The wheel adjustment means could of course be provided in various other forms using well-known technology. For example, a hydraulic or pneumatic cylinder could be provided for adjusting the radial position of each drive wheel 34 to accommodate different pipe sizes.

As illustrated in FIGS. 5A and 5B, the pipe drive mechanism preferably includes biasing means for biasing drive wheels 34 against a pipe 70 passing through pipe opening 32 so as to optimize the grip or traction between drive wheels 34 and pipe 70. In the Illustrated embodiment, the biasing means for each drive wheel 34 is provided in the form of a compression spring 42 disposed between sleeve 40 and bulkhead 30, radially outboard of the associated bracket 41. When there is no pipe passing through pipe opening 32, spring 42 biases wheel 34 toward (or even against) front face 30F of bulkhead 30, with the clear space between opposing drive wheels 34 being somewhat less than the diameter of the pipe to be installed. Therefore, when a pipe section 70 is then passed through pipe opening 32 in a direction toward front frame opening 23F, it will be tractively engaged by drive wheels 34 (which are being rotated by their respective hydraulic motors 36).

Springs 42 thus promote and maintain effective traction between drive wheels 34 and pipe 70. At the same time, they provide resiliency to accommodate imperfections in pipe 70 (for example, out-of-roundness), and to accommodate passage of pipe couplings 72 at connections between pipe sections where, as is common, the outer diameter of the coupling 72 is greater than that of pipe 70. As shown in FIG. 5B, the passage of a coupling 72 through pipe opening 32 is accommodated by additional compression of spring 42, which remains effective to keep drive wheels 34 in tractive engagement with pipe 70 (and coupling 72).

Persons skilled in the art of the invention will readily appreciate that other effective biasing means may be devised in accordance with known principles and technologies, without departing from the essential concepts of the present invention.

FIGS. 11 and 12 illustrate an alternative embodiment of the pipe drive mechanism having three pairs of drive wheels, with each pair of wheels being driven by a single hydraulic motor. A pair of spaced-apart upper wheels 34U are rotatably mounted in coplanar relation to a suitable upper beam structure 190U positioned above pipe opening 32 and extending between bulkhead 30 and a suitable upper support member 192U connected to or forming part of base structure 20. As shown in FIG. 11, upper wheels 340 are radially oriented relative to pipe opening 32. Each upper wheel 34U has a coaxially-mounted upper wheel sprocket 194U rotatable with upper wheel 34U. An upper motor support structure 1950U is mounted to upper beam 190U at a point between upper wheels 34U, and supports an upper hydraulic motor 361U which tarns an upper drive sprocket 196U lying in the same plane as upper wheel sprockets 194U. A continuous upper drive chain 198U is disposed around upper wheel sprockets 196U and upper drive sprocket 196U such that actuation of upper motor 36U will cause rotation of upper wheels 34U.

Upper motor support structure 195U may be of any suitable construction, and is preferably adapted to include or accommodate motor position adjustment means for adjusting the position of upper motor 36U relative to upper motor support structure 195U, to facilitate tensioning of upper drive chain 198U as may be required. In FIG. 12, the adjustment means is conceptually shown as incorporating an arm to which upper motor 36U is mounted and which is slidable within a sleeve member connected to upper beam structure 190U. However, persons skilled in the art will appreciate that the motor position adjustment means could take various other forms in accordance with well-known design principles and techniques.

In simple embodiments, upper beam structure 190U can be rigidly connected to its end supports (i.e., bulkhead 30 and upper support member 192U), with its position being set to accommodate a specific size of pipe 70. In preferred embodiments, though, upper beam 190U is mounted to its end supports using suitable wheel height adjustment means 199, thus allowing the radial position of upper wheels 34U, relative to pipe opening 32, to be adjusted to suit different sizes of pipe 70. In FIG. 12, wheel height adjustment means 199 is shown as comprising an upstand connected to upper beam 190U and slidable within a capped tubular sleeve connected to bulkhead 30 (or upper support member 192U), with a coil spring disposed between the upstand and the cap of the sleeve to bias upper wheels 34U radially toward a pipe 70 passing through pipe opening 32. A bolt 44 or pin passes through a hole (or holes) in the sleeve and through a vertically slot (or slots) in the upstand, such that the upstand is retained by and movable within the sleeve (to the extent allowed by the slots). Multiple holes can be provided in the sleeve to facilitate adjustment of wheel height adjustment means 199 to suit different pipe sizes.

The construction shown and described in connection with wheel height adjustment means 199 is for purposes of example only. Persons skilled in the art will appreciate that wheel height adjustment means 199 could take various other forms in accordance with well-known design principles and techniques.

Below upper beam structure 190U and pipe opening 32, a pair of lower beam structures 190L extend between bulkhead 30 and a suitable lower support member 194L connected to or forming part of base structure 20. A pair of spaced-part lower wheels 34L are ratably mounted to each lower beam 190L in substantially the same fashion as described in connection with upper wheels 34U. Each lower wheel 34L has a coaxially-mounted lower wheel sprocket 194L, rotatable with lower wheel 34L. A lower motor support structure 195L is mounted to each lower beam 190U at a point between lower wheels 34L, and supports a lower hydraulic motor 36L which turns a lower drive sprocket 196L lying in the same plane as lower wheel sprockets 194L. A continuous lower drive chain 198L is disposed around lower wheel sprockets 196L and lower drive sprocket 196L such, that actuation of lower motor 36L will cause rotation of lower wheels 34L.

As best seen in FIG. 11, the two pairs of lower wheels 34L are preferably disposed on either side of pipe opening 32 in a canted radial orientation, such that all upper wheels 34U and lower wheels 34L can tractively engage a pipe 70 passing through pipe opening 32, with all wheels' planes of rotation passing through or close to the longitudinal axis of pipe 70, thus optimizing tractive efficiency. In alternative embodiments, however, the planes of the two pairs of lower wheels 34L could both be vertical.

Although three sets of wheels are used in the embodiment shown In FIGS. 11 and 12, it would of course be feasible to use more than three sets. However, the use of three sets of wheels is particularly preferred since that configuration helps to ensure that all wheels will have substantially uniform contact with, pipe 70. Maximum tractive effectiveness with respect to pipe 70 is achieved by driving all wheels 34U and 34L, but this is not essential in one variant, only lower wheels 34L are driven, with upper wheels 340 being idlers; in another variant, only upper wheels 34U are driven, with lower wheels 34L being idlers.

Persons of ordinary skill in die art will appreciate that other variants of the drive mechanism of FIGS. 11 and 12 may be readily devised without departing from the principles of the present invention. To provide one non-limiting example, pulleys and drive belts could be used instead of sprockets and drive chains.

The operation of the pipe drive mechanism to advance pipe toward and through front frame opening 23F will necessarily result in an opposite reactive force acting against base structure 20. Accordingly, anchorage means must be provided to resist this reactive force in order to prevent rearward displacement of the apparatus 10 (i.e., to transfer the reactive force to the ground in the vicinity of apparatus 10). It may be possible in some operative circumstances, when the magnitude of the reactive force is small, for the anchorage means to be effectively provided by frictional or mechanical resistance between base structure 20 and the surface upon which it rests. In preferred embodiments, however, and as shown in FIGS. 1, 2, 3, and 6, the anchorage means is provided in the form of a pair of outriggers 26, one on either side of base structure 20. One end of each outrigger 26 is mounted to base structure 20 (preferably, but not necessarily, near front end 20F thereof) so as to be pivotable about a vertical axis. The other end of each outrigger 26 has an anchorage member 27 (such as a steel plate or blade) adapted to penetrate into and to be retained within a soil mass. Each outrigger 26 has a hydraulic, cylinder 28 extending; from a point near anchorage member 27 to a selected connection point on base structure 20. Actuation of hydraulic cylinder 28 is thus effective to move outrigger 26 in a generally horizontal plane between a stowed position (as shown in FIG. 2) and a deployed position (as shown in FIGS. 3 and 6). Effective result: have been achieved using hydraulic cylinders 28 having a 2-inch bore and an 8-inch stroke, with a working pressure of 3,000 pounds per square inch. However, hydraulic cylinders with other characteristics may be suitable or appropriate depending on site conditions arid desired operational, criteria.

It will be appreciated that the anchorage means described above and illustrated in the Figures represents an exemplary embodiment, and other effective anchorage means may be devised without departing from the principles of the present invention.

In simpler embodiments of the invention, pressure hydraulic fluid for actuating the hydraulic wheel motors and hydraulic cylinders of the anchorage means could be provided from a source external to apparatus 10. In preferred embodiments however, apparatus 10 is a self-contained unit, and therefore includes a power control system, conceptually indicated in FIGS. 1, 2, 3, and 6 as comprising a power module 50 and a control module 60. In the preferred embodiment, power module 50 incorporates a gas or diesel engine (with various accessories including a fuel tank), a hydraulic pump which is driven by the gas or diesel engine, and a hydraulic fluid reservoir. To provide one non-limiting example, beneficial results have been achieved using a 20-horsepower gas engine driving a Vickers™ Model 45D50A1A122R hydraulic pump with 1-inch lines. Control module 60 incorporates hydraulic system accessories such as manifolds, valves, and valve actuators for controlling flow of hydraulic fluid between the fluid reservoir and hydraulic motors 36 associated with drive wheels 34, via hydraulic hoses 37. In the preferred embodiment, power module 50 and control module 60 are mounted to base structure 20 in association with auxiliary rails 21 extending between rear frame 22R and bulkhead 30, but other mounting arrangements are possible without departing from the essential concept of the invention.

Persons skilled in the field of the invention will be sufficiently familiar with the principles of power systems and hydraulic drive and control systems so as to be readily able to devise one or more embodiments of a power module 50 and a control module 60 suitable for use with the present invention, without need to set out detailed hydraulic schematics or component particulars for purposes of this patent specification.

FIGS. 6, 7A, 7B, A, and 8B illustrate how the apparatus 10 of the invention may be deployed in the field for purposes of installing underground piping. As shown in FIG. 7A, a piping trench 80 is excavated along a desired path, using suitable equipment such as a conventional trackhoe. As may be seen from FIG. 6 and in particular from FIG. 7A, trench 80 may be comparatively narrow, with vertical or near-vertical sidewalls 80W if the soil is sufficiently cohesive. As indicated by reference characters 81, it may in some cases be desirable to backslope the upper regions of sidewalls 80W. If soil characteristics are such that sidewalls 80W require some amount of backsloping, the backslope angle can generally be significantly sleeper than would be warranted when installing pipe using safe trench methods.

In preferred embodiments of the method, a secondary channel 82 is excavated at the base of trench 80. Secondary channel 82 may be formed using any suitable method. Preferably, secondary channel 82 will be formed concurrently with trench 80, using a trackhoe with an auxiliary blade or “spoon” permanently or removably attached to, and extending downward from, the cutting edge of the trackhoe bucket. The geometry of the “spoon” will be selected to suit the desired cross-sectional dimensions of secondary channel 82, which, in turn will depend on the size of pipe to be installed in secondary channel 82. As desired, a different, size of “spoon” may be used for each pipe size; alternatively, a given size of “spoon” may be used for a range of pipe sizes.

The depth of trench 80 (and, in the preferred embodiment, secondary channel 82) needs to be controlled within reasonably close tolerances in order to ensure that the installed pipeline will be at the intended grade and slope. This is accomplished in accordance with well-known level surveying methods, preferably using a stationary surveyor's laser 200. For this purpose, and as may be seen in FIG. 7A, a laser support structure 210 may be provided at a convenience location, spanning trench 80, for supporting the laser 200, which emits a visible beam in a constant horizontal plane. As trench excavation proceeds, a worker carrying a surveyor's rod of suitable length holds the rod on the bottom of trench 80 in location as directed by the trackhoe operator. The laser beam intercepts the scale on the rod, enabling the trackhoe operator to determine the current depth of trench 80, and to determine the extent to which additional excavation may be required.

To prepare for use of the pipe installation apparatus 10 of the present, invention, a working zone 84 is excavated at the end of trench 80, generally as shown in FIGS. 6 and 7B. The length of working zone 84 (as measured parallel to trench 80) will preferably be in the range of 10 meters, but in general will be selected to suit various practical factors including the dimensions of apparatus 10 and the desired extent of worker access space around apparatus 10. Working zone 84 has sidewalls 84W which are backsloped in accordance with “safe trench” methods as appropriate to suit soil conditions. A machine pit 88, with sidewalls 88W, is excavated at the base of working zone 84 to accommodate apparatus 10, leaving a generally level access area 86 adjacent to apparatus 10 as appropriate. Machine pit 88 is excavated within reasonable tolerances to facilitate effective engagement of anchorage members 27 with sidewalls 88W. As best seen in FIG. 7B, machine pit 88 is excavated to art appropriate depth such that once apparatus 10 is positioned therein, front frame opening 23F, rear frame opening 23R, and pipe opening 32 of bulkhead 30 will be in general alignment, both horizontally and vertically, with the base of trench 80 (or, in the preferred, embodiment, with secondary channel 82).

After working zone 84 and machine pit 88 have been excavated, apparatus 10 is positioned in machine pit 88 as shown in FIGS. 6 and 7B. Outriggers 26 are then deployed, by actuation of hydraulic cylinder 28, such that their anchorage members 27 penetrate and securely engage sidewalls 88W of machine pit 88. As shown In FIGS. 7A and 8B, a layer of sand bedding 110 is deposited in the bottom of trench 80 (or, in the preferred embodiment, secondary channel 82). A first pipe section 70A is fed manually through rear frame opening 23R and pipe opening 32 so as to engage drive wheels 34, which in turn advance first pipe section 70 forward through front frame opening 23F. Leading end 72A of first, pipe section 70A is then engaged with a pipe sled 90 as shown in FIGS. 6, 7A, and 8B. Pipe sled 90 has a sole plate 92 adapted for sliding over sand bedding 110, with a contiguous upturned prow member 94 that prevents pipe sled 90 from digging downward into sand bedding 110. Pipe sled 90 also has a sleeve or bracket 96, of any suitable configuration, for receiving and retaining leading end 72A of first pipe section 70A.

The apparatus 10 is then activated so as to advance first pipe section 70A and pipe sled 90 into trench 80, with pipe sled 90 acting to level and to some extent compact sand bedding 110 as it passes thereover, and with the horizontal reactive force induced by this operation being transferred into sidewalls 88W of machine pit 88 through outriggers 26 and anchorage members 27. Pipe sled 90 may be suitably heavy or may have supplemental weighting to enhance its effectiveness for purposes of levelling and compacting sand bedding 110.

When the trailing end 74A first pipe section 70A approaches rear frame opening 23R, the forward advance of first pipe section 70 is temporarily stopped so that a second pipe section 70B can be coupled to trailing end 74A of first pipe section 70A. The apparatus 10 is then reactivated so as to advance the pipe string (comprising first and second pipe sections 70A and 70B) further into trench 80. Hits mode of operation is carried on, with additional pipe sections being added as required, until leading end 72A of first pipe section 70A has advanced to a desired final position. At that stage, apparatus 10 may be re-positioned in a second working zone 84 a selected distance back along trench 80. A second pipe string is then advanced into the trench until it meets and is coupled to the trailing edge of the first pipe string. This procedure is repeated as required until the entire pipeline required for the project has been laid in trench 80.

The distance between working zones 84 will be selected to suit a variety of factors, including but not limited to the size and weight of pipe being installed and the mechanical capabilities of the particular apparatus 10 being used. As a general rule, the power required to advance a pipe string into trench 80 will be greater for heavier pipe sections, and will increase as the length of the string increases. It has been found that working zone intervals in the range of 50 to 100 meters are typically sufficient for installing 6-inch to 12-inch plastic wafer mains, using an apparatus 10 compact enough to be transported on a half-ton truck. However, larger or smaller working zone intervals may be practical or desirable for particular combinations of variable design factors and project requirements.

At one or more locations along the length of the pipeline being installed, it will commonly be necessary to install valves, tees, cleanouts, or other fittings. To accommodate such fittings, the method of the invention provides for the installation of collapsible spacers (not shown) in such locations. The spacers may be of any suitable construction. In the preferred embodiment, however, each spacer comprises a first pipe section and a smaller second pipe section which can slide in telescopic fashion within the first pipe section. Preferably; each pipe section has a linearly-arrayed series of pin holes for receiving a retainer pin. The second pipe section is positioned as desired within the first pipe section, with at least one pin hole, of each pipe section being In alignment, whereupon one or more suitable retainer pins can be dropped through the aligned pin hole(s), thus temporarily fixing the length of the spacer (to suit the length of the fitting to be installed in the, spacer location). One end of the spacer will be a “male” end and the other end will be a “female” end, adapted for engagement with typical pipe sections 70 being laid in trench 80 (or secondary channel 82).

The collapsible spacers thus make it possible to install the full length of the pipeline, using the apparatus and method of the present invention, in a continuous fashion without needing to interrupt pipe-laying operations to install valves and tees and the like. After the pipeline has been laid out incorporating all required spacers, workers can enter a secondary “safe” working zone which has been excavated around each spacer to install the required fitting. The spacer is “collapsed” by removing the retainer pin(s) and then telescoping the two spacer sections, thus disengaging the spacer from adjacent pipe sections 70 to Which the spacer had been temporarily connected. The required valve or other fitting is then connected between the adjacent pipe sections 70.

After all spacers have been replaced with their corresponding valves, fees, or other fittings, the entire pipeline string is ready to be backfilled. Prior to that step, however, the connections between the various components are preferably made more secure by applying a compressive force to the string, so as to firmly seat all joints. Such a compressive force may be applied using the bucket of a trackhoe.

After all required pipeline strings have been positioned and connected as desired (and after the pipe installation, apparatus 10 has been removed), all trenches 80, secondary channels 82, working zones 84, and machine pits 88 may be backfilled and compacted as appropriate. In many if not most cases, it will necessary or desirable for the backfill 115 to be compacted to specified densities to prevent excessive settlement as backfill 115 consolidates over time, and methods and equipment for achieving such backfill densities are well known, in the interests of worker safety, however, it is desirable be able to compact, backfill 15 in narrow trenches 80 without the need for workers to descend into them.

For this reason, compaction of backfill 115 in trenches 80 is preferably carried out using a remote-control led articulated packer 120 as illustrated in. FIGS. 9 and 10. In the preferred embodiment, packer 120 has a front section 120A plus a rear section 120B of basically construction. Front section 120A has a roller drum 122A mounted to a peripheral frame 126A by means of suitable bearings 124; similarly, rear section 120B has a roller drum 122B mounted to a peripheral, frame 126B by bearings 124. Frames 126A and 126B are coupled by a suitable articulation linkage (conceptually indicated by reference character 160) whereby front and rear sections 120A and 120B may swivel relative to each other about a substantially vertical axis Z. The articulation linkage may incorporate steering means for selectively controlling relative swivelling of front and rear sections 120A and 120B. The steering means preferably will include at least one hydraulic steering ram, although other types of steering mechanisms may also be used. Although not essential, linkage 160 preferably will also provide for at least a limited degree of swivelling about a transverse horizontal axis.

Roller drums 122A and 122B are fabricated of steel plate in a fashion similar to rollers of known compaction equipment, with a continuous cylindrical outer plate 123 arid circular side plates 125 enclosing an inner chamber 127 that may be filled with ballasting material (such as water), in the illustrated embodiment, side plate 125 on roller drum 122A is inset a suitable distance from the edge of outer plate 123 to define a a recess 125F in which a suitable packer drive/braking mechanism (schematically indicated by reference character 150) may be disposed. The packer drive/braking mechanism could take a variety of forms, only a few of which are described or illustrated herein.

In preferred embodiments, the packer drive mechanism incorporates a reversible hydraulic motor having a “neutral” mode. In the preferred embodiment, the output shaft of the hydraulic motor is fitted with a drive sprocket that engages a drive chain attached to the outer lace of side plate 125 (such as by welding) in a circular configuration concentric with the drum's axle, thereby causing the drum to rotate in a selected direction. Alternatively, a sprocket, could be concentrically mounted to side plate 125, and driven by means of a drive chain disposed around the hydraulic motor's drive sprocket and the sprocket mounted to side plate 125.

The packer braking mechanism may work on principles analogous to automotive dram brakes, with one or more brake, shoes (with appropriately curved brake pads) that may be urged radially outward into contact with the inner face of outer plate 123 within recess 125F so as to retard and stop the rotation of the associated roller drum.

The sizes of roller drums 122A and 122B and their associated frames 126A and 126B will be determined to suit the width of trench 80 in which packer 120 is intended to be operated, as well as the roller mass required to achieve the desired level of backfill compaction. Satisfactory results have been achieved using roller drums having diameters of approximately 42 inches.

In the embodiment shown in FIG. 10, front section 120A of packer 120 has a platform 165 disposed above roller drum 122A and supported from frame 126A by suitable structural support members 132. The purpose of platform 165 is to support auxiliary components (schematically indicated by reference character 170) associated with packer drive/braking mechanism 150 and its remote control system. In preferred embodiments, the auxiliary components will include a hydraulic pump operably connected to the hydraulic motor of the packer's drive system, and a gas motor for driving the hydraulic pump.

The remote control system for the packer drive/braking mechanism 150 may be either a wireless (e.g., radio-controlled) or hard-wired system, in accordance with, well-known technology. In alternative embodiments, the packer may have a seat (and possibly a cab) for a riding operator, rather than being remotely controlled.

In preferred embodiments, as shown in FIG. 10, packer 120 has a second platform 130 carrying a water tank (schematically indicated by reference character 140), which may be used for adding water to backfill in the trench as may be required to achieve desired or required backfill compaction standards.

Also in preferred embodiments, packer 120 may be equipped with an adjustable “dozer” blade at either or both ends of packer 120 (as schematically indicated by reference characters 180A and 180B in FIG. 10). Dozer blades 180A and 180B will ideally be adjustable for both blade height and blade angle, by means of suitable hydraulic rams operably connected to a hydraulic pump included in auxiliary components 170. This pump could be the same pump that serves the hydraulic motor associated with packer drive/braking mechanism 150, or it could be a dedicated pump serving only the dozer blades.

It may be seen from the foregoing that the present invention enables she installation of utility in narrow and substantially straight-walled trenches, thus requiring considerably less excavation and backfill than in conventional pipe installation methods, while eliminating or limiting the need for workers to enter the trenches.

It will be readily appreciated by those skilled in the art that various modifications of the present invention may be devised without departing from the essential concept of the invention, and all such modifications are intended to come within the scope of the present invention.

In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following that word are included, but items not specifically mentioned are not excluded. A reference to an element by the Indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one such element. 

1. An apparatus structure installing piping in a trench, said apparatus comprising: (a) a base structure having a front end, a rear end, and a longitudinal axis; (b) a bulkhead attached to the base structure at a medial point between the front and rear ends of the base structure, said bulkhead being transverse to said longitudinal axis and having a pipe opening; and (c) a pipe drive mechanism mounted in association with the bulkhead; wherein said pipe drive mechanism comprises a plurality of wheels spaced around the pipe opening with their rotational axes generally transverse to the base structure's longitudinal axis, said wheels being engageable with a pipe extending through the pipe opening, with at least one of said wheels being a motor-driven wheel for applying a tractive force urging the pipe through the pipe opening.
 2. The apparatus of claim 1 wherein the plurality of wheels comprises three or more wheels mounted to the bulkhead and arranged in a radial pattern around the pipe opening.
 3. The apparatus of claim 1 wherein: (a) the plurality of wheels comprises three pairs of wheels, each pair of wheels being spaced apart in coplanar relation, and rotatably mounted to a wheel-support beam, extending between the bulkhead and a support member associated with the base structure; and (b) one or more pairs of wheels are motor-driven wheels.
 4. The apparatus of claim 3 wherein each pair of motor-driven wheels is driven by a single motor by means of a drive chain disposed around sprockets mounted to the motor and the motor-driven wheels.
 5. The apparatus of claim 3 wherein each pair of motor-driven wheels is driven by a single motor, by means of a drive belt disposed around pulleys mounted to the motor and the motor-driven wheels.
 6. The apparatus of claim 3 wherein the three pairs of wheels are arranged in a radial pattern around the pipe opening.
 7. The apparatus of claim 1, further comprising biasing means for biasing one or more of the wheels radially inward toward the pipe opening.
 8. The apparatus of claim 1, further comprising anchorage means.
 9. The apparatus of claim 8 wherein the anchorage means comprises a pair of outriggers pivotably mounted to the base structure, each outrigger having an anchorage member adapted to penetrate a soil mass.
 10. The apparatus of claim 1, further comprising means for adjusting the position of at least one of the wheels relative to the pipe opening.
 11. The apparatus of claim 1 wherein each motor-driven wheel is driven by a hydraulic motor, and further comprising: (a) a power module comprising a hydraulic pump, a hydraulic fluid reservoir, and an engine for driving the hydraulic pump; (b) a control module for controlling the flow of hydraulic fluid between the fluid reservoir and the one or more hydraulic motors.
 12. A method for installing an underground pipeline, said method comprising the steps of: (a) excavating an elongate trench; (b) excavating a working zone at a selected location along the length of the trench; (c) providing a pipe installation apparatus comprising: c.1 a base structure having a front end, a rear end, and a longitudinal axis: c.2 a bulkhead attached to the base structure at a medial point between the front and rear ends of the base structure, said bulkhead being transverse to said longitudinal axis and having a pipe opening; and c.3 a pipe drive mechanism mounted in association with, the bulkhead; wherein said pipe drive mechanism comprises a plurality of wheels spaced around the pipe opening with their rotational axes generally transverse to the base structure's longitudinal axis, said wheels being engageable with a pipe extending through the pipe opening, with at least one of said wheels being a motor-driven wheel for applying a tractive force urging the pipe through the pipe opening; (d) positioning the pipe installation apparatus within tire working zone such that: d.1 the longitudinal axis of the apparatus is in substantial alignment with the trench; and d.2 the pipe opening is at a selected elevation higher than the bottom of the trench; (e) feeding the lead end of a first pipe section through the pipe opening so as to engage the pipe drive mechanism, such that the lead end of the first pipe section is advanced into the trench; (f) temporarily disengaging the pipe drive mechanism after the first pipe section has been advanced a selected distance; (g) coupling the lead end of a second pipe section to the trailing end of the first pipe section, forming a pipe string; (h) activating the pipe drive mechanism to advance the pipe string further into the trench; and (i) coupling additional pipe sections to the pipe string and incrementally advancing the pipe string into the trench after each pipe section addition, until the pipe string of desired length has been advanced into the trench.
 13. The method of claim 12 comprising the further step of excavating a secondary channel along the length of the trench, for receiving the pipe string.
 14. The method of claim 12 further comprising the steps of; (a) installing granular bedding material in the trench prior to the first pipe section being advanced into the trench; and (b) engaging the lead end of the first pipe section with a pipe sled comprising a sole plate with an upturned prow member; such that as the pipe string is advanced into the trench with the pipe sled bearing on the granular material, the pipe sled also advances into the trench while smoothing die granular material beneath it.
 15. The method of claim 12 comprising the further step of installing spacer means at one or more positions along the length of the pipe string.
 16. The method of claim 12 comprising the further steps of: (a) placing backfill material in the trench, to cover the installed pipeline; and (b) compacting the backfill material using a packer comprising: b.1 front and rear sections each having a roller drum; b.2 an articulation linkage coupling the front and rear sections, said linkage being swivelable about a vertical axis; b.3 packer drive/braking means associated with a selected roller drum; b.4 steering means; and b.5 remote control means for controlling the drive/braking means and steering means.
 17. A packer for compacting backfill materials, said packer comprising: (a) front and rear sections each having a roller drum; (b) an articulation linkage coupling the front and rear sections, said linkage being swivelable about a vertical axis; (c) packer drive/braking means associated with a selected roller drum; (d) steering means; and (e) remote control means for controlling the drive/braking means and steering means.
 18. The packer of claim 17 wherein the packer drive/braking means and steering means are hydraulically actuated.
 19. The packer of claim 17 wherein the remote control means comprises a radio-controlled wireless system.
 20. The packer of claim 17, further comprising a hydraulically-actuated dozer blade associated with a selected one of the roller drums. 